Semiconductor fabrication processes have been developed which permit the integration of a very large number of transistors, diodes, and other circuit elements on a single integrated circuit. In semiconductor manufacture, a single semiconductor die (or chip) containing one or more integrated circuits can be packaged within a sealed package.
A semiconductor package can be a casing (made, for example, of ceramic, glass or metal) containing one or more semiconductor devices such as integrated circuits. Such packages generally provide a complex electrical lead system for connecting the integrated circuits on the die to the outside world.
To make connections between an integrated circuit and the leads of the package, wire bonds can be used, with fine wires connected from the package leads and bonded to conductive pads on the semiconductor die. At the outside of the package, wire leads may be soldered to a printed circuit board, for example, or other electrical devices, using solder balls.
A semiconductor package may have as few as two leads or contacts for devices such as diodes, or in the case of advanced microprocessors, a package may have hundreds of connections.
Many methods exist for packaging integrated circuits so that they can be electrically connected to an external device such as a printed circuit board. One method is the so called ball grid array (BGA) package. In a package configured with a Ball Grid Array (BGA), the IO connects for the package are distributed around the periphery of the package as well as over the bottom of the package. This configuration allows the BGA package to support more IO interfaces and provide more connectivity support for an integrated circuit with high circuit density and a high IO count.
Another configuration that has developed is the so-called flip chip configuration. In one example, a semiconductor device with a flip chip configuration has conductive pads formed on its bottom surface. The conductive pads might, for example, be in the form of C4 pads, and might be located on the bottom of silicon on which the semiconductor device is formed. The conductive pads are used to connect the semiconductor device to the substrate layer(s) of the semiconductor packaging. In such a configuration, electrical signals sent to or from the semiconductor device are transmitted through the conducting pads to circuitry and/or vias in the substrate layer(s) which in turn transmit the signals to or from the surface of the packaging There, the signals may be transmitted through solder balls located on the surface of the packaging which connect the semiconductor package to external devices or circuits. The conductive pads allow bonding to occur directly between the semiconductor device and the packaging, as well as providing I/O interfaces at a larger number of locations on the semiconductor device. In embodiments where such a flip chip configuration is not used, wire bonds connected to the top surface or sides of the semiconductor device may be used to connect the semiconductor device to the substrate, for example.
A semiconductor device typically has a plurality of Input/Output (IO) interfaces. The IO interfaces provide the semiconductor device with connections to external devices or systems. The configuration of these IO interfaces usually takes conventional forms. For example, IO blocks may be located on the outer edges of the semiconductor device in order to provide easy connection to routing wires which connect the semiconductor device to the outside world.
Effectively designing the location of a semiconductor device IO interfaces can produce routing efficiencies for the interconnects between the integrated circuits on the semiconductor device and the outside world. Such routing efficiencies in turn can provide cost benefits as well as improvements in device performance.